Phonomotor or a small-type electric motor for phonographs



June I 23, 1953 SABURO AKA 2,642,750

PHONOMOTOR on A SMALL-TYPE ELECTRIC MOTOR FOR PHONOGRAPHS Filed Aug. 9, 1950 I ll gmm

INVENTOR BY MPM ATTORNEY 5.

Patented June 23, 1953 PHONOMOTOR OR A SMALL-TYPE ELECTRIC MOTOR FOR PHONOGRAPHS Saburo Akai, Ohta-Ku, Tokyo, Japan Application August 9, 1950, Serial No. 178,432 In Japan October 22, 1949 This invention relates to a phonomotor, or a small-type electric motor for a phonograph.

Heretofore, in this kind of phonomotor, there has been aproblem how tov simplify its mechanism, and how to minimize the volume and size of the motor body. The present invention has for its first purpose to solve this problem.

Further, there has been aproblem how to offer a phonomotor capable of giving two kinds of revolutions, one being in the neighbourhood of 30 turns, and the other in the neighbourhood of 80 turns. The former is adapted for playing the ordinary records, and the other for playing the long-time records.

Further, there has been a problem how to extinguish the noisy sounds dueto the vibration, resonance and the like producedwithin the motor body, thereby giving exact sound of the records. The present invention has for its second purpose to solve this problem.

The third purpose of the present invention is to oifer such a phonomotor, which can give two kinds of revolutions just above mentioned.

According to the present invention, the first and third purposes are attained by the fact that the rotation of the motor is transmitted, by means of a speed-reducing gear, to a wheel axis, which in turn transmits the rotation, by means of a friction device, arranged on the wheel axis, to the shaft of the turn-table of a phonograph, so as to give the said shaft 2. number of revolutions of from 30 to 90 turns per minute, by shifting the position of the friction device.

The second purpose of the present invention is attained by the fact that the rotatory transmitting parts of the gear and the friction device are brought into contact through the intermediary of rubber or felt, thereby prohibiting completely any contact of metal parts.

Further, for attaining this second purpose, the motor body is provided on its upper edge with a cover. plate, which is attached to the motor body through the intermediary of rubber buffers, and the motorbody itself fixed to the phonograph cabinet by means of the cover plate. This pre- 2 Claims. (01. 74 194),

vents any sound or vibration liable to occur with- '1 number of the teeth formed on Now, referring to the drawings, 1' is an outer shell constituting the motor body, which is for housing the phonomotor of the present invention. The shell or the motor body is provided on its upper edge with a cover plate, which is attached to the body through the intermediary of rubber buifers 3, and the stop nut 4, the latter securing the cover plate to the body (see Fig. 4).

5 is a four-pole electric induction motor, of which the rotor has on its'extended part'a worm, which is adapted to mesh with a worm wheel 1, arranged on an axis 9, situated perpendicular to the axial line of the rotor. The worm wheel 1 is constructed of a central compressed felt 8, sandwiched between metal plates, and'has suitable teeth formed on its peripheral surface. Thus, the worm 6 and the worm wheel 1 are broughtinto coaction solely upon the felt surface, thereby preventing any contact of metal parts (see Fig. 5).

I0 is a sliding wheel having a rubber belt on its periphera1 surface stretched, and arranged on the wheel axis 9, to be slidable by means of a key groove [3 and a projecting piece engaging therein, the piece being arranged on the boss of the sliding wheel. By this means, the sliding wheel I0 is made capable of sliding axially, butprevented from self-rotation. v

I2 is a circular groove cut in the surface of the boss part of the sliding wheel l0, and adapted to receive therein the bifurcated extremity [5 of a steering lev'er [4 (see Fig. 3). This steering lever extends, as shown in Fig. 2, and is capableof being maneuvered from outside, so as tomake the sliding wheel slide on the axis 9.

I6 is a bearing disc so arranged as to coact, at its lower face, with the peripheral surface of the sliding wheel 10, and the boss part of the bearing disc is so formed as-to receive rigidly therein the lower end of the shaft ll of the turn-table [8 of a phonograph. Therefore, the whole weight of the turn-table, its shaft and thev bearing disc acts to make the peripheral surface of the sliding wheel coact frictionally with the lower face of the bearing disc. It is here noted that the shaft l1 pierces through the cover plate '2, extending downwards. J The function of the phonomotor according to the present invention is described below.

It is assumed that the number of revolutions of the rotor-of the electric motor is n, and t the the worm wheel 1, then'the axis 9 of the wheel I will have a number of revolutions, which is equal to 12/73, and accordingly, the sliding wheel I 0 revolves at the same number. Therefore, the number of revolutions of the bearing disc l6, which is rotated by frictionally coacting with the peripheral surface of the sliding wheel I0, is easily acquired by a formula known in respect to a friction device. That is, if it is assumed that a is the distance from the frictional coacting point of the sliding wheel to the centre of the bearing disc, b the diameter of the sliding wheel, and c the number of revolutions of the axis 8, then the number of revolutions given to the shaft I! of the turn-table of a phonograph is acquired by the formula: the number of revolutions is equal to (b/2a) xc.

For example, it is assumed that the number of revolutions of the rotor of the motor is 1420, then the number of revolutions given to the axis 9, and accordingly, to, the sliding wheel HI, is about 36. that the diameter of the sliding wheel is 40 cm., the diameter of the bearing disc 16 55 cm. and the distance from the frictional coacting point of the sliding wheel to the centre of the bearing disc 25 cm, then the number of revolutions given to the shaft 11, or the turntable I8, is equal to 40/(2 25 or about 28.8. Next, the said coacting point moved nearer to the centre of the bearing disc, for instance, to a point 9 cm. distant from the centre of the latter. Then, the number of revolutions given to the turn-table, or its shaft, is equal to ill/(2X9), or about 79.2.

From the above, it will be seen that according to the present invention the; turn-table can be given two kinds of revolutions, namely, one or e n i o ha b ing in the n hbourhQQd of 30 turns per minute, and the other corresponding to that being in the neighbourhood of 80, turns per minute. gives the advantage that the same and one phonograph is utilized for playing both the ordinary and the long-time records. In addition, according to the present invention this advantage is brought about by means of a much simplifiedarrange- "16. 9 b cause braking devices and/or other engaging devices, such as adopted in this kind Qt. nhonbmot r. are l mitt d,-

d eord ne t e n es t v nt on the p onomotor consists essentially of a motor and of ts. o ator nsmi g p r s uc as aworm ar and a r cti n d c h s; enables he cho omo qr b muc siimglifi c in nstru icn com act. i twei ht. d nim zed in size and volume considerably.

nally. as the worm 6 coactswiththe wheel I, solely upon the felt surface of the latter, w re s not. p cd c dany noisy ounds. due to the contact of metal parts. This is the same in case of the frictional coaction of the sliding wheel with the bearing disc, the coaction being effected solely upon the surface of the rubber belt ll, thereby doing away with any Contact of metal parts. Further, the cover plate 2, being attached to the body- I through the intermediary of rubber buffers 3, gives the aditers?v ha an sound. iable to occur within the body is prevented from being; transmitted. These means, put together, serve to extinguish h nois o nd able o occur in this. kind of phono notor.

What I claim is:

1. A phonograph comprising a casing which has a base andupstanding transverse side walls, a. cover mounted on the topsof said side walls and separated therefrom by shock absorbers, a

And. further, it is assumed.

motor mounted within said casing, said motor having a longitudinally extending driven worm shaft, a second shaft which extends laterally and which is turnably mounted in said casing, a worm wheel mounted on said second shaft, said worm wheel comprising a compressed felt body and end plates, said body being positioned between said plates and having teeth formed on its peripheral surface, the teeth of said worm shaft being operatively engaged with the teeth of said worm wheel whereby to drive said second shaft, a drive wheel mounted on said second shaft, a third shaft which extends transversely through a bearing opening in said cover, said third shaft being turnable about its axis and being axially slidable, a turntable mounted upon said third shaft above said cover, and a disc mounted on said third shaft below said cover, the axes of said second and third shafts being in a common plane, said drive wheel having a rubber rim, the lower face of said disc being positioned above said rim and being maintained in frictional abutment therewith solely by the weight of said turntable, said third shaft, and said disc, and means for moving said drive wheel axially on said second shaft under said lower face of said disc whereby to vary the speed of turning of said third shaft.

2. A phonograph comprising a casing which has side walls, a cover mounted on the tops of said side walls and separated therefrom by shock absorbers, a motor mounted within said casing and having a longitudinally extending driven worm shaft, a second shaft which extends laterally and which is turnably mounted in said casing, a worm wheel mounted on said second shaft and comprising a yieldable material body and end plates, said body being positioned between said plates and having teeth formed on its peripheral surface, the teeth of said worm shaft being operatively engaged with the teeth of said worm wheel whereby to drive said second shaft, a drive wheel mounted on said second shaft, a third shaft which extends transversely through a bearing opening in said cover, said third shaft being turnable about its axis and being axially slidable, a turntable mounted uponsaid third shaft above said cover, and a disc mounted on said third shaft below said cover, said drive wheel having a rubber rim, the lower face of said disc being positioned above said rim and being maintained in frictional abutment therewith solely by the weight of the assembly comprising said turntable, said disc and said third shaft, and means for moving said drive wheel axially on said second shaft under said lower face of said disc whereby to vary the speed of turning of said shaft.

SABURO AKAI.

References Cited. in the file of this patent UNITED STATES PATENTS Number Name Date 722,977 Hall Mar. 17, 1903 926,940 Hammett July 6, 1909 1,061,770 Miller May 13, 1913 1,196,899 Sturts Sept. 5, 1916 1,234,811 Shelton July 31, 1917 1,245,865 Bugbee Nov. 6, 1917 1,297,835 Guay Mar. 18, 1919 

